JP7507136B2 - Bioelectrode composition, bioelectrode, and method for producing bioelectrode - Google Patents

Description

The present invention relates to a bioelectrode that can be brought into contact with the skin of a living body and detect bodily conditions such as heart rate by electrical signals from the skin, a method for producing the same, and a bioelectrode composition suitable for use in the bioelectrode.

In recent years, the development of wearable devices has progressed along with the spread of IoT (Internet of Things). Typical examples are watches and glasses that can connect to the Internet. Furthermore, in the medical and sports fields, there is a demand for wearable devices that can constantly monitor the condition of the body, and these are expected to be growth areas in the future.

In the medical field, wearable devices that monitor the state of the body's organs by sensing weak currents, such as in electrocardiograms, which detect the movement of the heart through electrical signals, are being considered. In electrocardiograms, electrodes coated with conductive paste are attached to the body to perform the measurement, but this is a one-time, short-term measurement. In contrast, the aim of developing medical wearable devices such as those described above is to develop devices that constantly monitor health conditions for several consecutive days. Therefore, bioelectrodes used in medical wearable devices are required to have no change in conductivity even when used for long periods of time and not cause skin allergies. In addition to these, they also need to be lightweight and able to be manufactured at low cost.

As the novel coronavirus spreads around the world, the need for home medical care is being called into question in order to prevent the collapse of medical care due to the hospitalization of so many virus-infected people that hospital capacity is exceeded. Online medical examinations that would allow doctors in hospitals to diagnose the health of people at home have been proposed, and for this there is a demand for the development of low-cost, highly accurate wearable devices.

Medical wearable devices include those that are attached to the body and those that are incorporated into clothing. As for the type that is attached to the body, a bioelectrode that uses a water-soluble gel containing water and electrolytes, which are the materials for the conductive paste mentioned above, has been proposed (Patent Document 1). The water-soluble gel contains sodium, potassium, and calcium as electrolytes in a water-soluble polymer that holds water, and converts changes in ion concentration from the skin into electricity. On the other hand, as for the type that is incorporated into clothing, a method has been proposed that uses a conductive polymer such as PEDOT-PSS (Poly-3,4-ethylenedioxythiophene-Polystyrenesulfonate) or cloth with silver paste incorporated into the fibers as an electrode (Patent Document 2).

However, when using the above-mentioned water-soluble gel containing water and electrolytes, there is a problem that the conductivity is lost when the water dries out. On the other hand, when using metals with a high tendency to ionize, such as copper, there is a problem that some people may experience skin allergies, and when using conductive polymers such as PEDOT-PSS, there is a problem that the surplus polystyrene sulfonic acid that is not used to dope the conductive polymer is highly acidic, so there is a risk of skin allergies, and there is also a problem that the conductive polymer peels off from the fibers during washing.

In addition, because of their excellent electrical conductivity, the use of metal nanowires, carbon black, carbon nanotubes, and the like as electrode materials has also been considered (Patent Documents 3, 4, and 5). Metal nanowires have a high probability of contact between wires, so they can conduct electricity with a small amount of additive. However, metal nanowires are thin materials with sharp tips, which can cause skin allergies. Carbon nanotubes are also irritating to living organisms for the same reason. Carbon black is not as toxic as carbon nanotubes, but it is slightly irritating to the skin. Thus, even if the material itself does not cause an allergic reaction, the shape and irritation of the material can cause the material to have poor biocompatibility, making it difficult to achieve both electrical conductivity and biocompatibility.

Metal films have extremely high electrical conductivity, so one would think they would function as excellent bioelectrodes, but this is not necessarily the case. When the heart beats, not only a weak current is released from the skin, but also sodium ions, potassium ions, and calcium ions. For this reason, it is necessary to convert the change in ion concentration into electrical current, but precious metals, which are difficult to ionize, are inefficient at converting ions from the skin into electrical current. Therefore, bioelectrodes that use precious metals have high impedance, and there is high resistance to electrical current passing through the skin.

Bioelectrodes with added ionic polymers have been proposed (Patent Documents 6, 7, 8). Bioelectrodes made by adding ionic polymers and carbon powder to a silicone adhesive have adhesive properties and are highly water repellent, making it possible to stably collect biosignals even when attached to the skin for long periods of time after showering or sweating. Ionic polymers do not pass through the skin, so they are not irritating to the skin and are highly biocompatible, which also makes it possible to wear the bioelectrode for long periods of time.

Silicone is an insulator by nature, but the combination of ionic polymer and carbon powder improves its ionic conductivity, allowing it to function as a bioelectrode. However, there is a demand for further improvements in performance through improved ionic conductivity.

Printable electronics, in which devices are manufactured by printing, are attracting attention. If it becomes possible to produce biomedical devices using roll-to-roll printing, it will be possible to reduce costs by improving productivity. Printable electronics also have the characteristics of being lightweight and thin. They need to be light, thin, small and compact in order to reduce the feeling of contact when attached to the skin.

Wearable devices must be attached to the skin for several days and then removed without leaving any residue on the skin. Bioelectrodes in particular must not only be sufficiently adhesive to be attached to the skin, but also have sufficient film strength to prevent residue from being left behind after removal.

To produce bioelectrodes by printing, a time margin is required between mixing the ink for printing bioelectrodes and printing, or between printing and baking to harden the film. Without this time margin, for example, there would be no time leeway between mixing the ink and printing, and time would have to be strictly controlled, making it impossible to respond if a sudden problem caused the printing equipment to stop. For stable production by printing, materials are needed that ensure a time leeway between mixing the ink and printing and hardening the film.

International Publication No. 2013/039151 JP 2015-100673 A Japanese Patent Application Laid-Open No. 5-095924 JP 2003-225217 A JP 2015-019806 A JP 2018-99504 A JP 2018-126496 A JP 2018-130533 A

The present invention has been made to solve the above problems, and aims to provide a bioelectrode composition that can form a biocontact layer for a bioelectrode that is highly conductive and biocompatible, lightweight, can be manufactured at low cost, and leaves no residue on the skin after being attached to the skin and removed, a bioelectrode in which a biocontact layer is formed from the bioelectrode composition, and a method for manufacturing the same.

To achieve the above objectives, the present invention proposes the following bioelectrode composition and bioelectrode.

That is, the present invention provides a bioelectrode composition containing (A) an ionic polymer material, (B) an addition reaction curing type silicone having at least a hydrosilyl group, (C) a platinum group catalyst, and a solvent, characterized in that the water content in the bioelectrode composition is 0.2 mass% or less, and the solvent contains one or more of ether-based, ester-based, and ketone-based solvents that do not contain a hydroxyl group, a carboxyl group, a nitrogen atom, or a thiol group.

The bioelectrode composition of the present invention can form a biocontact layer for a bioelectrode that is highly conductive and biocompatible, lightweight, and can be manufactured at low cost, and does not leave any residue on the skin after application and removal.

The bioelectrode composition is a mixture of a solution containing the ionic polymer material as component (A), an addition reaction curing type silicone having at least a hydrosilyl group as component (B), and a solution containing the platinum group catalyst as component (C), and the moisture content in both component (A) and component (B) can be 0.2 mass% or less.

In such a bioelectrode composition, the moisture content of components (A) and (B) is low, so that the deactivation reaction of the hydrosilyl group does not proceed immediately after mixing components (A) and (B). Even if components (A), (B), and (C) are mixed and left to stand to form a bioelectrode, no residue is left on the skin when the bioelectrode is attached to the skin, a biosignal is acquired, and then the bioelectrode is peeled off.

In this case, the solvent of the solution of component (A) is one or more of ether-based, ester-based, and ketone-based solvents that do not contain hydroxyl groups, carboxyl groups, nitrogen atoms, or thiol groups, and component (B) can be solvent-free or a solution of a hydrocarbon-based or ether-based solvent.

The ionic polymeric material of component (A) is highly polar and therefore easily dissolves in one or more of these ether, ester and ketone solvents, while the organosilicon having hydrosilyl groups of component (B) is easily dissolved in hydrocarbon or ether solvents (solvent-free is also acceptable). When mixing components (A) and (B), mixing can be carried out quickly if the ionic polymeric compound (polymeric material) is dissolved in a solvent beforehand.

In addition, in the bioelectrode composition of the present invention, it is preferable that the ionic polymer material in the component (A) is a polymer compound containing a repeating unit having a structure selected from the sodium salt, potassium salt, and silver salt of any of fluorosulfonic acid, fluorosulfonimide, and N-carbonylfluorosulfonamide.

Such a bioelectrode composition is excellent in electrical conductivity and biocompatibility, lightweight, and can be manufactured at low cost, and can be used to form a biocontact layer for a bioelectrode that does not lose electrical conductivity significantly whether it is wet or dried.

（式中、Ｒｆ_１、Ｒｆ_２は水素原子、フッ素原子、酸素原子、メチル基、又はトリフルオロメチル基であり、Ｒｆ_１が酸素原子の時、Ｒｆ_２も酸素原子であり、結合する炭素原子とともにカルボニル基を形成し、Ｒｆ_３、Ｒｆ_４は水素原子、フッ素原子、又はトリフルオロメチル基であり、かつ、Ｒｆ_１～Ｒｆ_４のうち１つ以上はフッ素原子又はトリフルオロメチル基である。Ｒｆ_５、Ｒｆ_６、Ｒｆ_７は、フッ素原子、炭素数１～４の直鎖状、又は炭素数３、４の分岐状のアルキル基であり、少なくとも１つ以上のフッ素原子を有する。ｍは１～４の整数である。Ｍはナトリウム、カリウム、又は銀である。） In this case, the structure is preferably one represented by the following general formulas (1)-1 to (1)-4.

(In the formula, Rf ₁ and Rf ₂ are a hydrogen atom, a fluorine atom, an oxygen atom, a methyl group, or a trifluoromethyl group. When Rf ₁ is an oxygen atom, Rf ₂ is also an oxygen atom and forms a carbonyl group together with the carbon atom to which it is bonded. Rf ₃ and Rf ₄ are a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of Rf ₁ to Rf ₄ is a fluorine atom or a trifluoromethyl group. Rf ₅ , Rf ₆ , and Rf ₇ are a fluorine atom, a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 3 or 4 carbon atoms, and have at least one fluorine atom. m is an integer of 1 to 4. M is sodium, potassium, or silver.)

Such a bioelectrode composition can further improve the effects of the present invention.

（式中、Ｒ^１、Ｒ^３、Ｒ^５、Ｒ^８、Ｒ^１０、Ｒ^１１、及びＲ^１３は、それぞれ独立に水素原子又はメチル基であり、Ｒ^２、Ｒ^４、Ｒ^６、Ｒ^９、及びＲ^１２は、それぞれ独立に単結合、エステル基、あるいはエーテル基、エステル基のいずれか又はこれらの両方を有していてもよい炭素数１～１３の直鎖状、炭素数３～１２の分岐状又は環状の２価炭化水素基のいずれかである。Ｒ^７は、炭素数１～４の直鎖状、又は炭素数３～１２の分岐状のアルキレン基であり、Ｒ^７中の水素原子のうち、１個又は２個がフッ素原子で置換されていてもよい。Ｘ_１、Ｘ_２、Ｘ_３、Ｘ_４、及びＸ_６は、それぞれ独立に単結合、フェニレン基、ナフチレン基、エーテル基、エステル基、アミド基のいずれかであり、Ｘ_５は、単結合、エーテル基、エステル基のいずれかであり、Ｘ_７は、単結合、炭素数６～１２のアリーレン基、又は－Ｃ（＝Ｏ）－Ｏ－Ｘ_１０－であり、Ｘ_１０は炭素数１～１２の直鎖状、分岐状、環状のアルキレン基、又は炭素数６～１０の２価の芳香族炭化水素基であり、Ｘ_１０中にエーテル基、カルボニル基、エステル基を有していても良い。Ｙは酸素原子、又は－ＮＲ^１９－基であり、Ｒ^１９は水素原子、炭素数１～４の直鎖状、又は炭素数３、４の分岐状のアルキル基であり、ＹとＲ^４とは結合し環を形成していてもよい。ｍは１～４の整数である。ａ１、ａ２、ａ３、ａ４、ａ５、ａ６、及びａ７は、０≦ａ１≦１．０、０≦ａ２≦１．０、０≦ａ３≦１．０、０≦ａ４≦１．０、０≦ａ５≦１．０、０≦ａ６≦１．０、０≦ａ７≦１．０であり、０＜ａ１＋ａ２＋ａ３＋ａ４＋ａ５＋ａ６＋ａ７≦１．０を満たす数である。Ｍ、Ｒｆ_５、Ｒｆ_６、Ｒｆ_７は前述と同様である。） Furthermore, it is preferable that the one or more repeating units selected from the sodium salt, potassium salt, and silver salt of fluorosulfonic acid represented by general formula (1)-1 or (1)-2, sulfonimide represented by (1)-3, or sulfonamide represented by (1)-4 have one or more repeating units selected from repeating units a1 to a7 represented by general formula (2) below.

(In the formula, R ¹ , R ³ , R ⁵ , R ⁸ , R ¹⁰ , R ¹¹ and R ¹³ are each independently a hydrogen atom or a methyl group; R ² , R ⁴ , R ⁶ , R ⁹ and R ¹² are each independently a single bond, an ester group, or a linear, branched or cyclic divalent hydrocarbon group having 1 to 13 carbon atoms which may have an ether group, an ester group or both; R ⁷ is a linear, branched or cyclic alkylene group having 1 to 4 carbon atoms or a branched alkylene group having 3 to 12 carbon atoms, and one or two of the hydrogen atoms in R ⁷ may be substituted with a fluorine atom; X ₁ , X ₂ , X ₃ , X ₄ and X ₆ are each independently a single bond, a phenylene group, a naphthylene group, an ether group, an ester group or an amide group; X _{X 5} is a single bond, an ether group, or an ester group, X ₇ is a single bond, an arylene group having 6 to 12 carbon atoms, or -C(=O)-O-X ₁₀ -, X ₁₀ is a linear, branched, or cyclic alkylene group having 1 to 12 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 10 carbon atoms, and X ₁₀ may have an ether group, a carbonyl group, or an ester group. Y is an oxygen atom or a -NR ¹⁹ - group, R ¹⁹ is a hydrogen atom, or a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 3 or 4 carbon atoms, and Y and R ⁴ may be bonded to form a ring. m is an integer of 1 to 4. a1, a2, a3, a4, a5, a6, and a7 are numbers satisfying 0≦a1≦1.0, 0≦a2≦1.0, 0≦a3≦1.0, 0≦a4≦1.0, 0≦a5≦1.0, 0≦a6≦1.0, and 0≦a7≦1.0, and 0<a1+a2+a3+a4+a5+a6+a7≦1.0. M, Rf ₅ , Rf ₆ , and Rf ₇ are the same as those described above.

Such a bioelectrode composition can further improve the effects of the present invention.

In addition, in the present invention, the component (B) may contain an organopolysiloxane having a hydrosilyl group.

The (B) component may also contain a diorganopolysiloxane having an alkenyl group in addition to an organopolysiloxane having a hydrosilyl group.

In the bioelectrode composition of the present invention, such component (B) can be suitably used.

The component (B) may further contain a silicone resin having R _x SiO _(4-x)/2 units (R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and x is in the range of 2.5 to 3.5) and SiO ₂ units.

When this type of component (B) is included, the adhesive strength is improved.

In addition, in the present invention, the component (A) may contain a diorganosiloxane having an alkenyl group in addition to the ionic polymer material.

Component (A) can be suitably used in the bioelectrode composition of the present invention.

The component (A) may further contain a silicone resin having R _x SiO _(4-x)/2 units (R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and x is in the range of 2.5 to 3.5) and SiO ₂ units.

When this type of component (A) is included, the adhesive strength is improved.

In addition, the present invention may further include, as component (D), one or more selected from carbon powder, metal powder, silicon powder, lithium titanate powder, and metal chloride powder contained in component (A) or component (B).

The conductivity can be further improved by further adding such conductive powders (carbon powder, metal powder, silicon powder, lithium titanate powder, and metal chloride powder).

In this case, the carbon powder is preferably any one of carbon black, graphite, and carbon nanotubes, or a combination of these, and may further contain ionic components.

This would allow for even greater improvement in conductivity.

The metal powder is preferably a metal powder selected from gold, silver, platinum, copper, tin, titanium, nickel, aluminum, tungsten, molybdenum, ruthenium, chromium, and indium, with silver powder being particularly preferred.

Such a material can increase electronic conductivity.

The present invention also provides a method for producing the bioelectrode composition, which is characterized in that the (A) ionic polymer material, the (B) addition reaction curing type silicone having at least a hydrosilyl group, and the (C) platinum group catalyst are stored in separate containers, and when producing a bioelectrode, they are mixed to produce the bioelectrode composition.

The method for producing a bioelectrode composition of the present invention makes it possible to efficiently and at low cost produce a bioelectrode composition that is excellent in electrical conductivity and biocompatibility, lightweight, and capable of forming a biocontact layer for a bioelectrode that leaves no residue on the skin after application to the skin and removal.

In addition, in the method for producing a bioelectrode composition of the present invention, the (D) component can be mixed into the (A) component or the (B) component before or simultaneously with mixing the (C) component.

This method of manufacturing the bioelectrode composition can reduce the effect of moisture derived from component (D).

The present invention also provides a bioelectrode having a conductive substrate and a biocontact layer formed on the conductive substrate, the bioelectrode being characterized in that the biocontact layer is a cured product of the bioelectrode composition.

The bioelectrode of the present invention has excellent electrical conductivity and biocompatibility, is lightweight, and leaves no residue on the skin after application and removal.

In this case, it is preferable that the conductive substrate contains one or more selected from gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, carbon, and conductive polymers.

In the present invention, such conductive substrates can be suitably used.

The present invention also provides a method for producing a bioelectrode having a conductive substrate and a biocontact layer formed on the conductive substrate, characterized in that the bioelectrode composition is applied to the conductive substrate and cured to form the biocontact layer.

The manufacturing method of the bioelectrode of the present invention makes it possible to efficiently and inexpensively manufacture a bioelectrode that is highly conductive and biocompatible, lightweight, and leaves no residue on the skin after it is attached to the skin and removed.

In this case, it is preferable to use a conductive substrate containing one or more metals selected from gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, carbon, and conductive polymers.

In the present invention, such conductive substrates can be suitably used.

As described above, the bioelectrode composition of the present invention contains (A) an ionic polymer material, (B) an addition reaction curing type silicone having at least a hydrosilyl group, (C) a platinum group catalyst, and a solvent, and the water content in the bioelectrode composition is 0.2 mass% or less, and the solvent contains at least one of ether-based, ester-based, and ketone-based solvents that do not contain a hydroxyl group, a carboxyl group, a nitrogen atom, or a thiol group. The bioelectrode composition can harden a film without inhibiting the addition reaction when mixing, applying, and baking the components (A) to (C), and has sufficient film strength. After attaching the bioelectrode to the skin to measure a biosignal and peeling it off, no residue is left on the skin. Even if the time between mixing (A) to (C) and printing or the time between printing and baking is long, sufficient film strength is maintained and no residue is left after peeling. If the components (A) to (C) are stored in separate containers, deterioration does not occur due to long-term storage.

In addition, the bioelectrode of the present invention has sufficient adhesiveness, a constant contact area with the skin, and can obtain electrical signals from the skin stably and with high sensitivity.

In addition, the manufacturing method of the bioelectrode of the present invention makes it possible to easily manufacture the bioelectrode of the present invention, which has excellent electrical conductivity and biocompatibility, is lightweight, and does not significantly decrease in electrical conductivity whether it is wet or dried, by low-cost printing.

FIG. 1 is a schematic cross-sectional view showing an example of a bioelectrode of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of the bioelectrode of the present invention attached to a living body. FIG. 2 is a schematic diagram of a bioelectrode produced in an example of the present invention after printing. FIG. 2 is a schematic diagram showing one of the bioelectrodes produced in the examples of the present invention cut out and with an adhesive layer attached. FIG. 2 is a diagram showing the locations where electrodes and a ground are attached to the human body when measuring a biosignal in an embodiment of the present invention. 1 is a diagram showing an electrocardiogram waveform obtained using a bioelectrode according to an embodiment of the present invention.

As described above, there has been a demand for the development of a bioelectrode composition capable of forming a biocontact layer for a bioelectrode that is highly conductive and biocompatible, lightweight, can be manufactured at low cost, and leaves no residue on the skin after application to the skin and removal from the skin, a bioelectrode in which a biocontact layer is formed from the bioelectrode composition, and a manufacturing method thereof.

A weak electric current and sodium, potassium, and calcium ions are released from the skin surface in tandem with the heartbeat, and a bioelectrode must convert the increase or decrease in these ions released from the skin into an electrical signal. Therefore, to construct a bioelectrode, a material with excellent ionic conductivity is required to transmit the increase or decrease in ions.

The present inventors focused on ionic liquids as a material with high ionic conductivity. Ionic liquids have the characteristics of high thermal and chemical stability and excellent conductivity, and are being widely used in battery applications. In addition, hydrochlorides, hydrobromides, hydroiodides, trifluoromethanesulfonates, nonafluorobutanesulfonates, bis(trifluoromethanesulfonyl)imidates, hexafluorophosphate salts, tetrafluoroborate salts, etc. of sulfonium, phosphonium, ammonium, morpholinium, pyridinium, pyrrolidinium, and imidazolium are known as ionic liquids. However, since these salts (especially those with small molecular weights) generally have high hydration properties, bioelectrodes in which a biocontact layer is formed using a bioelectrode composition to which these salts have been added have the disadvantage that the salts are extracted by sweat or washing, resulting in a decrease in conductivity. In addition, tetrafluoroborate salts are highly toxic, and other salts are highly water-soluble, so they easily penetrate into the skin, causing rough skin (i.e., they are highly irritating to the skin).

When the acid that forms the neutralized salt is highly acidic, the ions are strongly polarized, improving ionic conductivity. This is why lithium salts of bis(trifluoromethanesulfonyl)imide acid and tris(trifluoromethanesulfonyl)methide acid show high ionic conductivity in lithium-ion batteries. On the other hand, the higher the acid strength, the stronger the bioirritation of the salt. In other words, there is a trade-off between ionic conductivity and bioirritation. However, salts used in bioelectrodes must have both high ionic conductivity and low bioirritation.

The larger the molecular weight of the salt compound, and the higher the three-dimensional structure, the less permeable it is to the skin, and the less irritating it is to the skin. Therefore, the inventors came up with the idea of adding an ionic polymer compound to the bioelectrode composition.

The inventors further came up with the idea that by mixing this salt into an adhesive (resin), it would be possible to obtain a stable electrical signal for a long period of time while maintaining constant contact with the skin. As an adhesive, they considered it preferable to use a silicone adhesive from the viewpoints of biocompatibility, skin breathing, and suppressing deformation of the skin and redness when the adhesive is removed.

Silicone adhesives consist of a hybrid of cross-linkable silicone and MQ resin, and the cross-linking reaction used is either radical cross-linking caused by the decomposition of peroxide or a hydrosilylation reaction between hydrosilyl groups and vinyl groups. The addition of carbon to the bioelectrode composition is effective in improving conductivity, but because carbon absorbs radicals, it cannot be added in the case of radical-based cross-linking reactions. On the other hand, carbon does not inhibit the hydrosilylation reaction.

Hydrosilyl groups react with water and compounds that have active protons, such as hydroxyl groups, carboxyl groups, and thiol groups. For example, when hydrosilyl groups react with water, they become silanol groups, and the hydrosilylation reaction with vinyl groups does not proceed. Therefore, in order to proceed with the hydrosilylation reaction, the water content must be low, and compounds that have active protons, such as hydroxyl groups, carboxyl groups, and thiol groups, cannot be added as solvents.

It is not silicone having hydrosilyl groups (B) that is likely to contain water, but solutions containing ionic polymer compounds (polymer materials) (A). When mixed with solution (B), the water contained in solution (A) causes a deactivation reaction of the hydrosilyl groups. Therefore, solutions containing ionic polymer compounds (A) must be dehydrated. Dehydration can be performed by using a dehydrating agent such as azeotropic dehydration or molecular sieves to increase the concentration of the solution containing the ionic polymer compounds.

As a result of intensive research into the above-mentioned problems, the inventors have discovered that if the water content in the bioelectrode composition is low and the content of compounds having active protons such as hydroxyl groups, carboxyl groups, and thiol groups is also low, the deactivation reaction of hydrosilyl groups when mixed with these is suppressed and the hydrosilylation reaction is not inhibited, and that a bioelectrode formed from a bioelectrode composition in which the water content and the content of compounds having active protons are thus limited does not leave any residue on the skin after being applied to the skin and then peeled off, thus completing the present invention.

That is, the present invention is a bioelectrode composition containing (A) an ionic polymer material, (B) an addition reaction curing type silicone having at least a hydrosilyl group, (C) a platinum group catalyst, and a solvent, characterized in that the water content in the bioelectrode composition is 0.2 mass% or less, and the solvent contains one or more of ether-based, ester-based, and ketone-based solvents that do not contain a hydroxyl group, a carboxyl group, a nitrogen atom, or a thiol group.

The present invention will be described in detail below, but the present invention is not limited thereto.
In the following description, each component includes a solution containing that component.

<Bioelectrode composition>
The bioelectrode composition of the present invention is characterized in that it contains (A) an ionic polymer material, (B) an addition reaction curing type silicone having at least a hydrosilyl group, (C) a platinum group catalyst, and a solvent, the moisture content in the bioelectrode composition is 0.2 mass% or less, and the solvent contains one or more of ether-based, ester-based, and ketone-based solvents that do not contain a hydroxyl group, a carboxyl group, a nitrogen atom, or a thiol group. As described later, it can contain other components than the above (A) to (C) as necessary.

If the water content in the bioelectrode composition is high, the hydrosilyl group of the silicone in the composition reacts with water to form a silanol group, and crosslinking due to the hydrosilyl reaction between Si-H groups and Si-vinyl groups in the presence of a platinum group catalyst does not proceed. If the crosslinking reaction does not proceed, the strength of the film is weakened, and when the bioelectrode is attached and then peeled off, internal destruction of the film occurs, and a residue of the bioelectrode is left on the skin.
In particular, in the case of a bioelectrode composition obtained by mixing (A) a solution containing an ionic polymer material, (B) an addition reaction curing type silicone, and (C) a solution containing a platinum group catalyst, if the water content of each of the solutions of the components (A) and (B) exceeds 0.2 mass%, the hydrosilyl group of the silicone in the component (B) after mixing reacts with water to form a silanol group, and the above tendency becomes prominent.

(A) If the solution containing an ionic polymeric material contains hydroxyl groups, carboxyl groups, nitrogen atoms, or thiol groups, a reaction between the solvent and hydrosilyl groups will occur, and the proportion of hydrosilyl groups will decrease, inhibiting the hydrosilylation reaction. Ionic polymeric materials are highly polar and therefore easily soluble in solvents that contain hydroxyl groups, carboxyl groups, nitrogen atoms, or thiol groups, but they must be dissolved in ether, ester, or ketone solvents that do not contain these groups.

Therefore, in the bioelectrode composition of the present invention, it is essential that the water content in the composition is 0.2 mass% or less, and the solvent contains at least one of ether-based, ester-based, and ketone-based solvents that do not contain a hydroxyl group, a carboxyl group, a nitrogen atom, or a thiol group. The water content in the solvent, solution, and bioelectrode composition can be measured by the Karl Fischer method.
The bioelectrode composition of the present invention will be described in detail below.

[Component (A)]
The component (A) is an ionic polymer material. Silicone is an insulator by nature, but when combined with an ionic polymer (ionic polymer material), its ionic conductivity is improved and it functions as a bioelectrode. The ionic polymer material is not particularly limited as long as it has ionic conductivity.

The ionic polymer material is preferably a polymer compound containing a repeating unit having a structure selected from the group consisting of sodium salts, potassium salts, and silver salts of fluorosulfonic acid, fluorosulfonimide, and N-carbonylfluorosulfonamide.
A bioelectrode composition containing such an ionic polymer compound can be used to form a biocontact layer for a bioelectrode that has excellent electrical conductivity and biocompatibility, is lightweight, and can be manufactured at low cost, and whose electrical conductivity does not decrease significantly whether it is wetted with water or dried.

（式中、Ｒｆ_１、Ｒｆ_２は水素原子、フッ素原子、酸素原子、メチル基、又はトリフルオロメチル基であり、Ｒｆ_１が酸素原子の時、Ｒｆ_２も酸素原子であり、結合する炭素原子とともにカルボニル基を形成し、Ｒｆ_３、Ｒｆ_４は水素原子、フッ素原子、又はトリフルオロメチル基であり、かつ、Ｒｆ_１～Ｒｆ_４のうち１つ以上はフッ素原子又はトリフルオロメチル基である。Ｒｆ_５、Ｒｆ_６、Ｒｆ_７は、フッ素原子、炭素数１～４の直鎖状、又は炭素数３、４の分岐状のアルキル基であり、少なくとも１つ以上のフッ素原子を有する。ｍは１～４の整数である。Ｍはナトリウム、カリウム、又は銀である。） Furthermore, the ionic repeating unit having the above structure is more preferably one represented by any one of the following general formulas (1)-1 to (1)-4.

(In the formula, Rf ₁ and Rf ₂ are a hydrogen atom, a fluorine atom, an oxygen atom, a methyl group, or a trifluoromethyl group. When Rf ₁ is an oxygen atom, Rf ₂ is also an oxygen atom and forms a carbonyl group together with the carbon atom to which it is bonded. Rf ₃ and Rf ₄ are a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of Rf ₁ to Rf ₄ is a fluorine atom or a trifluoromethyl group. Rf ₅ , Rf ₆ , and Rf ₇ are a fluorine atom, a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 3 or 4 carbon atoms, and have at least one fluorine atom. m is an integer of 1 to 4. M is sodium, potassium, or silver.)

（式中、Ｒ^１、Ｒ^３、Ｒ^５、Ｒ^８、Ｒ^１０、Ｒ^１１、及びＲ^１３は、それぞれ独立に水素原子又はメチル基であり、Ｒ^２、Ｒ^４、Ｒ^６、Ｒ^９、及びＲ^１２は、それぞれ独立に単結合、エステル基、あるいはエーテル基、エステル基のいずれか又はこれらの両方を有していてもよい炭素数１～１３の直鎖状、炭素数３～１２の分岐状又は環状の２価炭化水素基のいずれかである。Ｒ^７は、炭素数１～４の直鎖状、又は炭素数３～１２の分岐状のアルキレン基であり、Ｒ^７中の水素原子のうち、１個又は２個がフッ素原子で置換されていてもよい。Ｘ_１、Ｘ_２、Ｘ_３、Ｘ_４、及びＸ_６は、それぞれ独立に単結合、フェニレン基、ナフチレン基、エーテル基、エステル基、アミド基のいずれかであり、Ｘ_５は、単結合、エーテル基、エステル基のいずれかであり、Ｘ_７は、単結合、炭素数６～１２のアリーレン基、又は－Ｃ（＝Ｏ）－Ｏ－Ｘ_１０－であり、Ｘ_１０は炭素数１～１２の直鎖状、分岐状、環状のアルキレン基、又は炭素数６～１０の２価の芳香族炭化水素基であり、Ｘ_１０中にエーテル基、カルボニル基、エステル基を有していても良い。Ｙは酸素原子、又は－ＮＲ^１９－基であり、Ｒ^１９は水素原子、炭素数１～４の直鎖状、又は炭素数３、４の分岐状のアルキル基であり、ＹとＲ^４とは結合し環を形成していてもよい。ｍは１～４の整数である。ａ１、ａ２、ａ３、ａ４、ａ５、ａ６、及びａ７は、０≦ａ１≦１．０、０≦ａ２≦１．０、０≦ａ３≦１．０、０≦ａ４≦１．０、０≦ａ５≦１．０、０≦ａ６≦１．０、０≦ａ７≦１．０であり、０＜ａ１＋ａ２＋ａ３＋ａ４＋ａ５＋ａ６＋ａ７≦１．０を満たす数である。Ｍ、Ｒｆ_５、Ｒｆ_６、Ｒｆ_７は前述と同様である。） Furthermore, it is even more preferable that the ionic repeating unit is selected from a1 to a7 in the following general formula (2).

(In the formula, R ¹ , R ³ , R ⁵ , R ⁸ , R ¹⁰ , R ¹¹ and R ¹³ are each independently a hydrogen atom or a methyl group; R ² , R ⁴ , R ⁶ , R ⁹ and R ¹² are each independently a single bond, an ester group, or a linear, branched or cyclic divalent hydrocarbon group having 1 to 13 carbon atoms which may have an ether group, an ester group or both; R ⁷ is a linear, branched or cyclic alkylene group having 1 to 4 carbon atoms or a branched alkylene group having 3 to 12 carbon atoms, and one or two of the hydrogen atoms in R ⁷ may be substituted with a fluorine atom; X ₁ , X ₂ , X ₃ , X ₄ and X ₆ are each independently a single bond, a phenylene group, a naphthylene group, an ether group, an ester group or an amide group; X _{X 5} is a single bond, an ether group, or an ester group, X ₇ is a single bond, an arylene group having 6 to 12 carbon atoms, or -C(=O)-O-X ₁₀ -, X ₁₀ is a linear, branched, or cyclic alkylene group having 1 to 12 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 10 carbon atoms, and X ₁₀ may have an ether group, a carbonyl group, or an ester group. Y is an oxygen atom or a -NR ¹⁹ - group, R ¹⁹ is a hydrogen atom, or a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 3 or 4 carbon atoms, and Y and R ⁴ may be bonded to form a ring. m is an integer of 1 to 4. a1, a2, a3, a4, a5, a6, and a7 are numbers satisfying 0≦a1≦1.0, 0≦a2≦1.0, 0≦a3≦1.0, 0≦a4≦1.0, 0≦a5≦1.0, 0≦a6≦1.0, and 0≦a7≦1.0, and 0<a1+a2+a3+a4+a5+a6+a7≦1.0. M, Rf ₅ , Rf ₆ , and Rf ₇ are the same as those described above.

Specific examples of monomers for obtaining the ionic repeating units selected from a1 to a7 in the above general formula (2) are described in paragraphs [0061] to [0091] of JP 2020-002342 A, and the monomers, copolymerization ratios, polymerization methods, molecular weights, and the like for copolymerizing therewith can be those described in paragraphs [0112] to [0135].

When mixing an ionic polymer compound with an organosilicon having a hydrosilyl group, the mixing can be carried out quickly if the ionic polymer compound is dissolved in a solvent beforehand. The solvent for dissolving the ionic polymer compound is preferably an ether-, ester- or ketone-based solvent that has a water content of 0.2 mass% or less and does not have active protons such as hydroxyl groups, carboxyl groups, or thiol groups.

Examples of ether solvents for dissolving ionic polymer compounds include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol methyl butyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether, propylene glycol methyl propyl ether, propylene glycol methyl butyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol divinyl ether, diethylene glycol diallyl ether, diethylene glycol dipropyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl butyl ether, diethylene glycol methyl phenyl ether, diethylene glycol methyl benzyl ether, and diethylene glycol bis(2-propynyl) ether. Specific examples of the ketone solvent include cyclopentanone, 2-carbonylethoxycyclopentanone, 2-methoxycarbonylcyclopentanone, 2-ethoxycarbonylcyclopentanone, 2-heptylcyclopentanone, 2,2,4-trimethylcyclopentanone, 2-cyclopentylcyclopentanone, 2-acetylcyclopentanone, 2-cyclopenten-1-one, 3-methyl-2-cyclopentenone, 2-pentyl-2-cyclopenten-1-one, 2-amyl-3-methyl-2-cyclopenten-1-one, cyclohexanone, 3,3,5-trimethylcyclohexanone, 4,4-dimethylcyclohexanone, 2-methoxycyclohexanone, 2-propylcyclohexanone, 4-propylcyclohexanone, 3,4-dimethylcyclohexanone, 3,3-dimethylcyclohexanone, 2-cyclohexylcyclohexanone, 2-allylcyclohexanone, 2-cyclohexyl ... Cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, 4-tert-butylcyclohexanone, 2-acetylcyclohexanone, 4,4,dimethylcyclohexanone, 3,5-dimethylcyclohexanone, 4-ethylcyclohexanone, 2-sec-butylcyclohexanone, 2-cyclohexen-1-one, 3-methyl-2-cyclohexen-1-one, 4,4-dimethyl Examples of such methyl 2-cyclohexen-1-one include methyl-2-cyclohexen-1-one, 3,5,5-trimethyl-2-cyclohexen-1-one, cycloheptanone, 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclopentanone, methyl n-pentyl ketone, acetophenone, methylacetophenone, propiophenone, and isobutyrophenone.

Ester solvents include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol diacetate, diethylene glycol monoethyl ether acrylate, diethylene glycol monomethyl ether methacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, ethyl pyruvate, butyl acetate, pentyl acetate, hexyl acetate, heptyl acetate, isobutyl acetate, amyl acetate, butenyl acetate, isoamyl acetate, phenyl acetate, propyl formate, butyl formate, isobutyl formate, amyl formate, formic acid Isoamyl, methyl valerate, methyl pentenoate, methyl crotonate, ethyl crotonate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono tert-butyl ether acetate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate , ethyl phenylacetate, 2-phenylethyl acetate, gamma-butyrolactone, alpha-methyl-gamma-butyrolactone, alpha-angelica lactone, delta-valerolactone, gamma-valerolactone, beta-methyl-gamma-valerolactone, alpha-methylene-gamma-butyrolactone, gamma-methylene-gamma-butyrolactone, gamma-caprolactone, epsilon-caprolactone, gamma-heptalactone, gamma-octalactone, whiskey lactone, gamma-nonalactone, delta-nonalactone, etc.

[Component (B)]
Component (B) is an addition reaction curing type silicone having at least a hydrosilyl group, and is not particularly limited as long as it has a hydrosilyl group and cures by an addition reaction.
The (B) component may be a matrix resin, or may be compatible with the (A) component to prevent the elution of salt, retain a conductivity enhancer, etc., if present, and exhibit adhesion.

Component (B) can be one which contains an organopolysiloxane having a hydrosilyl group, one which contains a diorganopolysiloxane having an alkenyl group in addition to an organopolysiloxane having a hydrosilyl group, or one which further contains a silicone resin having R _x SiO _(4-x)/2 units (R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and x is in the range of 2.5 to 3.5) and SiO ₂ units.
Examples of such materials include those described in JP 2015-193803 A that contain diorganosiloxanes having alkenyl groups, MQ resins having R ₃ SiO _0.5 and SiO ₂ units, and organohydrogenpolysiloxanes having multiple SiH groups (hydrosilyl groups).

When preparing the bioelectrode composition of the present invention, a solution (A) containing an ionic polymeric material is mixed with a polysiloxane (B) containing a hydrosilyl group. It is preferable that the polysiloxane molecule contains multiple hydrosilyl groups.

In order to develop adhesiveness, a silicone resin having R _x SiO _(4-x)/2 units (R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and x is in the range of 2.5 to 3.5) and SiO ₂ units can be added to either or both of component (A) and component (B), and it is preferable to mix a diorganosiloxane having an alkenyl group, and an MQ resin having R ₃ SiO _0.5 and SiO ₂ units, as described in JP 2015-193803 A.

It is also possible to use a polysiloxane-resin integrated compound formed by the condensation reaction of polysiloxane having silanols at the polymer end or side chain with MQ resin. MQ resin contains a lot of silanols, so adding this improves adhesive strength, but since it is not crosslinkable, it is not molecularly bonded to the polysiloxane. By integrating polysiloxane and resin as described above, adhesive strength can be increased. By including multiple alkenyl groups in the above polysiloxane, adhesive strength is further increased by the crosslinking reaction with hydrosilyl groups.

[solvent]
The bioelectrode composition of the present invention contains a solvent. Each component may contain a solvent, and the solvents may be the same or different. The solvent can improve workability by dissolving or dispersing each component. On the other hand, some solvents contain moisture from the beginning or due to moisture absorption, etc., so that the moisture content in the bioelectrode composition increases when they are used. In this case, the hydrosilyl group of the silicone in the composition reacts with water to form a silanol group, and crosslinking by hydrosilyl reaction between Si-H groups and Si-vinyl groups in the presence of a platinum group catalyst does not proceed. If the crosslinking reaction does not proceed, the film strength is weakened, and when the bioelectrode is attached and peeled off, internal destruction of the film occurs, and a residue of the bioelectrode is generated on the skin.
In addition, ionic polymer materials are highly polar and therefore easily soluble in solvents containing hydroxyl groups, carboxyl groups, nitrogen atoms, or thiol groups. However, when such solvents are used, a reaction occurs between active hydrogen in the solvent and hydrosilyl groups, reducing the proportion of hydrosilyl groups and inhibiting the hydrosilylation reaction.
In the present invention, therefore, in consideration of improving workability and suppressing deactivation of hydrosilyl groups, the solvent contains at least one of ether-based, ester-based, and ketone-based solvents that do not contain a hydroxyl group, a carboxyl group, a nitrogen atom, or a thiol group. The solvent used in the present invention may contain such a specific solvent, and may further contain other solvents.

The bioelectrode composition of the present invention may have a water content of 0.2% by mass or less in the entire final composition, and if such a composition is obtained, the water content of the solvent used may exceed 0.2% by mass. However, from the viewpoint of suppressing deactivation of hydrosilyl groups due to moisture, it is preferable that the water content of both components (A) and (B) is 0.2% by mass or less, and it is more preferable that the water content of all components other than component (C) is 0.2% by mass or less. Note that the platinum group catalyst (C) has a small mixing ratio with respect to the entire composition, and even if it contains moisture, it can be said that the water content of the entire final composition is 0.2% by mass or less. Therefore, the moisture in component (C) is not particularly problematic. The lower the moisture content, the better, but it can be in the range of 0.0001 to 0.2% by mass, for example.
The dehydration treatment of the solvent may be carried out by a conventional method, for example, by azeotropic dehydration or by using a dehydrating agent such as molecular sieves, etc. The dehydration treatment may be carried out in advance or during the process of preparing the composition.

In addition, a hydrocarbon-based organic solvent or an ether-based organic solvent can be added as component (B) to the bioelectrode composition of the present invention. Specific examples of the hydrocarbon-based organic solvent include toluene, xylene, cumene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, styrene, α-methylstyrene, butylbenzene, sec-butylbenzene, isobutylbenzene, cymene, diethylbenzene, 2-ethyl-p-xylene, 2-propyltoluene, 3-propyltoluene, 4-propyltoluene, 1,2,3,5-tetramethyltoluene, 1,2,4,5-tetramethyltoluene, tetrahydronaphthalene, 4-phenyl-1-butene, tert-amylbenzene, amylbenzene, 2-tert-butyltoluene, 3-tert-butyltoluene, 4- Aromatic hydrocarbon solvents such as tert-butyltoluene, 5-isopropyl-m-xylene, 3-methylethylbenzene, tert-butyl-3-ethylbenzene, 4-tert-butyl-o-xylene, 5-tert-butyl-m-xylene, tert-butyl-p-xylene, 1,2-diisopropylbenzene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, dipropylbenzene, pentamethylbenzene, hexamethylbenzene, hexylbenzene, and 1,3,5-triethylbenzene, n-heptane, isoheptane, 3-methylhexane, 2,3-dimethylpentane, 3-ethylpentane, 1,6-heptadiene, and 5-methyl-1-hexyne. , norbornane, norbornene, dicyclopentadiene, 1-methyl-1,4-cyclohexadiene, 1-heptyne, 2-heptyne, cycloheptane, cycloheptene, 1,3-dimethylcyclopentane, ethylcyclopentane, methylcyclohexane, 1-methyl-1-cyclohexene, 3-methyl-1-cyclohexene, methylenecyclohexane, 4-methyl-1-cyclohexene, 2-methyl-1-hexene, 2-methyl-2-hexene, 1-heptene, 2-heptene, 3-heptene, n-octane, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,3-dimethylhexane, 3,4-dimethyl Hexane, 3-ethyl-2-methylpentane, 3-ethyl-3-methylpentane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane, cyclooctane, cyclooctene, 1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane, ethylcyclohexane, vinylcyclohexane, isopropylcyclopentane, 2,2-dimethyl-3-hexene, 2,4-dimethyl-1-hexene, 2,5-dimethyl-1-hexene, 2,5-dimethyl-2-hexene, 3,3-dimethyl-1-hexene, 3,4-dimethyl-1-hexene, 4,4-dimethyl ethyl-1-hexene, 2-ethyl-1-hexene, 2-methyl-1-heptene, 1-octene, 2-octene, 3-octene, 4-octene, 1,7-octadiene, 1-octyne, 2-octyne, 3-octyne, 4-octyne, n-nonane, 2,3-dimethylheptane, 2,4-dimethylheptane, 2,5-dimethylheptane, 3,3-dimethylheptane, 3,4-dimethylheptane, 3,5-dimethylheptane, 4-ethylheptane, 2-methyloctane, 3-methyloctane, 4-methyloctane, 2,2,4,4-tetramethylpentane, 2,2,4-trimethylhexane, 2,2,5-trimethylhexane, 2,2-dimethyl-3-heptene, 2,3-dimethyl aryl-3-heptene, 2,4-dimethyl-1-heptene, 2,6-dimethyl-1-heptene, 2,6-dimethyl-3-heptene, 3,5-dimethyl-3-heptene, 2,4,4-trimethyl-1-hexene, 3,5,5-trimethyl-1-hexene, 1-ethyl-2-methylcyclohexane, 1-ethyl-3-methylcyclohexane, 1-ethyl-4-methylcyclohexane, propylcyclohexane, isopropylcyclohexane, 1,1,3-trimethylcyclohexane, 1,1,4-trimethylcyclohexane, 1,2,3-trimethylcyclohexane, 1,2,4-trimethylcyclohexane, 1,3,5-trimethylcyclohexane, allylcyclohexane, aryl Dorindane, 1,8-nonadiene, 1-nonyne, 2-nonyne, 3-nonyne, 4-nonyne, 1-nonene, 2-nonene, 3-nonene, 4-nonene, n-decane, 3,3-dimethyloctane, 3,5-dimethyloctane, 4,4-dimethyloctane, 3-ethyl-3-methylheptane, 2-methylnonane, 3-methylnonane, 4-methylnonane, tert-butylcyclohexane, butylcyclohexane, isobutylcyclohexane, 4-isopropyl-1-methylcyclohexane, pentylcyclopentane, 1,1,3,5-tetramethylcyclohexane, cyclododecane, 1-decene, 2-decene, 3-decene, 4-decene, 5-decene, 1,9-decadiene, decahydro Naphthalene, 1-decyne, 2-decyne, 3-decyne, 4-decyne, 5-decyne, 1,5,9-decatriene, 2,6-dimethyl-2,4,6-octatriene, limonene, myrcene, 1,2,3,4,5-pentamethylcyclopentadiene, α-phellandrene, pinene, terpinene, tetrahydrodicyclopentadiene, 5,6-dihydrodicyclopentadiene, dicyclopentadiene, 1,4-decadiyne, 1,5-decadiyne, 1,9-decadiyne, 2,8-decadiyne, 4,6-decadiyne, n-undecane, amylcyclohexane, 1-undecene, 1,10-undecadiene, 1-undecyne, 3-undecyne, 5-undecyne, tricyclo[6.2.1.0 Examples of the aliphatic hydrocarbon solvent include ^2,7 ]undec-4-ene, n-dodecane, 2-methylundecane, 3-methylundecane, 4-methylundecane, 5-methylundecane, 2,2,4,6,6-pentamethylheptane, 1,3-dimethyladamantane, 1-ethyladamantane, 1,5,9-cyclododecatriene, 1,2,4-trivinylcyclohexane, and isoparaffin. Examples of the isoparaffin solvent include Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, Isopar M, and Isopar V (manufactured by Standard Oil).
Specific examples of ether-based organic solvents include diisopropyl ether, diisobutyl ether, diisopentyl ether, di-n-pentyl ether, methylcyclopentyl ether, methylcyclohexyl ether, di-n-butyl ether, di-sec-butyl ether, di-sec-pentyl ether, di-tert-amyl ether, di-n-hexyl ether, anisole, 3-methoxytoluene, 4-methoxytoluene, trans-anethole, etc. In order to suppress deactivation of the hydrosilyl group, the organic solvent may be one that does not have a hydroxyl group, a carboxyl group, a nitrogen atom, or a thiol group.

The amount of solvent added is preferably in the range of 10 to 50,000 parts by mass per 100 parts by mass of the resin of component (A) or component (B).

[Component (C)]
The diorganosiloxane having an alkenyl group and the organohydrogenpolysiloxane having a plurality of hydrosilyl groups can be crosslinked by an addition reaction in the presence of a platinum group catalyst, component (C).

Examples of the platinum group catalyst of component (C) include platinum catalysts such as chloroplatinic acid, alcohol solutions of chloroplatinic acid, reaction products of chloroplatinic acid and alcohol, reaction products of chloroplatinic acid and olefin compounds, reaction products of chloroplatinic acid and vinyl group-containing siloxane, platinum-olefin complexes, platinum-vinyl group-containing siloxane complexes, and platinum group metal catalysts such as rhodium complexes and ruthenium complexes. These catalysts may also be dissolved or dispersed in alcohol-based, hydrocarbon-based, or siloxane-based solvents.

The amount of platinum group catalyst added should be an effective amount, but it is preferable to add it in the range of 5 to 2,000 ppm, and particularly 10 to 500 ppm, per 100 parts by mass of resin.

In the above silicone-based resin, in addition to the above-mentioned diorganosiloxane having _an alkenyl group, MQ resin having _R3SiO0.5 and _SiO2 units, and organohydrogenpolysiloxane having a plurality of hydrosilyl groups, the compatibility with the above-mentioned salt is improved by adding a modified siloxane having a group selected from an amino group, an oxirane group, an oxetane group, a polyether group, a hydroxy group, a carboxyl group, a mercapto group, a methacryl group, an acrylic group, a phenol group, a silanol group, a carboxylic anhydride group, an aryl group, an aralkyl group, an amide group, an ester group, and a lactone ring.

As described below, the biocontact layer is a cured product of the bioelectrode composition. By curing, the adhesion of the biocontact layer to both the skin and the conductive substrate is improved.

In addition, when an addition-curing silicone resin is used, an addition reaction inhibitor may be added to component (A) or component (B). This addition reaction inhibitor is added as a quencher to prevent the platinum group catalyst from acting in the solution and in the low-temperature environment before heat curing after coating formation. Specific examples include 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclohexanol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethylsiloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy-1-hexyne, 1-ethynyl-1-trimethylsiloxycyclohexane, bis(2,2-dimethyl-3-butynoxy)dimethylsilane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,1,3,3-tetramethyl-1,3-divinyldisiloxane.

The amount of addition reaction inhibitor added is not particularly limited, but it is preferable to add it in the range of 0 to 10 parts by weight, and especially 0.05 to 3 parts by weight, per 100 parts by weight of resin.

[Component (D)]
The bioelectrode composition of the present invention can further contain a conductive powder as component (D). The conductive powder is not particularly limited as long as it is a powder having conductivity, but is preferably one or more selected from carbon powder (carbon material), metal powder, silicon powder, lithium titanate powder, and metal chloride powder, and more preferably carbon powder and/or metal powder. It is preferable that component (D) is mixed in advance in component (A) or component (B). By further adding such a conductive powder (carbon powder, metal powder, etc.), the conductivity can be further improved. In the following, the conductive powder is also called "conductivity improver".

[Carbon powder]
Carbon materials (carbon powder) can be added as the conductivity enhancer. Examples of carbon materials include carbon black, graphite, carbon nanotubes, and carbon fibers. The carbon nanotubes may be either single-layered or multi-layered, and the surface may be modified with an organic group. The carbon powder may further contain ion components, that is, ions may be adsorbed or contained on the surface or inside of the carbon material (carbon powder). By adsorbing or containing ions in the carbon material, the ionic conductivity can be further improved, and the sensitivity of the biosignal can be further increased. To adsorb or contain ions in the carbon powder, a method of dispersing the carbon powder in a solution containing ions and heating the solution while stirring, or a method of implanting ions into the carbon powder can be mentioned. The amount of carbon material added is preferably in the range of 1 to 50 parts by mass per 100 parts by mass of the resin.

[Metal powder]
In order to increase the electronic conductivity, it is preferable to add a metal powder selected from gold, silver, platinum, copper, tin, titanium, nickel, aluminum, tungsten, molybdenum, ruthenium, chromium, and indium as component (D) to the bioelectrode composition of the present invention. The amount of the metal powder added is not particularly limited, but is preferably in the range of 1 to 50 parts by mass per 100 parts by mass of the resin.

As for the types of metal powder, gold, silver, and platinum are preferred from the viewpoint of electrical conductivity, and silver, copper, tin, titanium, nickel, aluminum, tungsten, molybdenum, ruthenium, and chromium are preferred from the viewpoint of cost. From the viewpoint of biocompatibility, precious metals are preferred, and from these viewpoints overall, silver is the most preferred.

The shape of the metal powder can be spherical, disk-like, flake-like, or needle-like, but the addition of flake-like powder is the most conductive and is therefore preferred. The size of the metal powder is not particularly limited, but flakes having a relatively low density and large specific surface area of 100 μm or less, a tap density of 5 g/cm ³ or less, and a specific surface area of 0.5 m ² /g or more are preferred. Both metal powder and carbon material (carbon powder) can also be added as the conductivity enhancer.

[Silicon powder]
In the bioelectrode composition of the present invention, silicon powder can be added as component (D) to enhance the sensitivity of ion reception. Examples of silicon powder include powders made of silicon, silicon monoxide, and silicon carbide. The particle size of the powder is not particularly limited, but is preferably smaller than 100 μm, and more preferably 1 μm or less. Since finer particles have a larger surface area, more ions can be received, resulting in a highly sensitive bioelectrode. The amount of silicon powder added is not particularly limited, but is preferably in the range of 1 to 50 parts by mass per 100 parts by mass of resin.

[Lithium titanate powder]
In the bioelectrode composition of the present invention, lithium titanate powder can be added as component (D) to enhance the sensitivity of ion reception. Examples of lithium titanate powder include the molecular formulas Li ₂ TiO ₃ , LiTiO ₂ , and Li ₄ Ti ₅ O ₁₂ with a spinel structure, with the spinel structure being preferred. Lithium titanate particles composited with carbon can also be used. The particle size of the powder is not particularly limited, but is preferably smaller than 100 μm, more preferably 1 μm or less. Since finer particles have a larger surface area, they can receive more ions, resulting in a highly sensitive bioelectrode. These may be composite powders with carbon. The amount of lithium titanate powder added is not particularly limited, but is preferably in the range of 1 to 50 parts by mass per 100 parts by mass of resin.

[Metal chloride powder]
In the bioelectrode composition of the present invention, a metal chloride powder can be added as component (D) to improve ionic conductivity. Examples of the metal chloride powder include alkali metal chlorides such as sodium chloride and potassium chloride, which are ionic additives described later, and alkaline earth metal chlorides such as calcium chloride and magnesium chloride. Among them, sodium chloride and potassium chloride are preferred. The particle size of the powder is not particularly limited, but is preferably smaller than 100 μm, and more preferably 1 μm or less. Since finer particles have a larger surface area, they can function as ion carriers more efficiently, resulting in a highly sensitive bioelectrode. These may be composite powders with carbon (carbon powder further containing ionic components derived from metal chlorides). To incorporate carbon powder, the above-mentioned method of incorporating ionic components into carbon powder can be used. For example, carbon powder such as graphite or carbon black can be added to an aqueous solution of metal chlorides such as sodium chloride or potassium chloride, or an alcohol dispersion such as methanol, and stirred while heating as necessary, and then the solvent (water, methanol, etc.) is evaporated to obtain ion-treated carbon powder. The amount of metal chloride powder added is not particularly limited, but is preferably in the range of 1 to 50 parts by mass per 100 parts by mass of the resin.

The particle diameter (size) of the metal powder or the like can be the particle diameter at 50% of the cumulative value in the volume-based particle size distribution determined by the laser diffraction/scattering method (D50). Measurement by the laser diffraction/scattering method can be performed, for example, using a Microtrack particle size analyzer MT3300EX (manufactured by Nikkiso Co., Ltd.).

[Component (E)]
The bioelectrode composition of the present invention can further contain additives as component (E) if necessary.Additives can include moisturizing components such as polyether, polyglycerin, polyglycerin ester, polyether silicone, polyglycerin silicone, and salts such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium saccharin, potassium acesulfame, sodium carboxylate, potassium carboxylate, calcium carboxylate, sodium sulfonate, potassium sulfonate, calcium sulfonate, sodium phosphate, potassium phosphate, calcium phosphate, magnesium phosphate, and betaine for improving ionic conductivity.Additives can also include silicone compounds and inorganic particles having a polyglycerin structure as described below.

(Tackifier)
In addition, a tackifier may be added to the bioelectrode composition to impart adhesion to the living body. Examples of such tackifiers include silicone resins, non-crosslinked siloxanes, non-crosslinked poly(meth)acrylates, and non-crosslinked polyethers.

(Crosslinking Agent)
An epoxy-based crosslinking agent can be added to the bioelectrode composition. In this case, the crosslinking agent is a compound having multiple epoxy groups or oxetane groups in one molecule. The amount of the crosslinking agent added is 1 to 30 parts by mass per 100 parts by mass of the resin.

(Crosslinking catalyst)
A catalyst for crosslinking epoxy groups or oxetane groups can also be added to the bioelectrode composition. In this case, the catalysts described in paragraphs 0027 to 0029 of JP-A-2019-503406 can be used. The amount of the catalyst added is 0.01 to 10 parts by mass per 100 parts by mass of the resin.

(Ionic Additives)
Ionic additives for increasing ionic conductivity can be added to the bioelectrode composition. In consideration of biocompatibility, sodium chloride, potassium chloride, calcium chloride, saccharin sodium salt, acesulfame potassium, and salts described in JP-A-2018-44147, JP-A-2018-59050, JP-A-2018-59052, and JP-A-2018-130534 can be mentioned.

(Silicone compound having a polyglycerin structure)
In the bioelectrode composition of the present invention, a silicone compound having a polyglycerin structure can be added in order to improve the moisture retention of the membrane and improve the sensitivity and ion conductivity of ions released from the skin. The amount of the silicone compound having a polyglycerin structure is not particularly limited, but is preferably 0.01 to 100 parts by mass, more preferably 0.5 to 60 parts by mass, per 100 parts by mass of the total of the (A) component and the (B) component. The silicone compound having a polyglycerin structure may be used alone or in a mixture of two or more types.

（式（４）および（５）中、Ｒ^１’は、それぞれ独立であり、互いに同一であっても異なっていても良く、水素原子または炭素数１～５０の直鎖状若しくは分岐状のアルキル基、又はフェニル基であり、エーテル基を含有していても良く、一般式（６）で示されるシリコーン鎖であってもよく、Ｒ^２’は式（４）－１又は式（４）－２で表されるポリグリセリン基構造を有する基であり、Ｒ^３’は、それぞれ独立であり、互いに同一であっても異なっていても良く、前記Ｒ^１’基又は前記Ｒ^２’基であり、Ｒ^４’は、それぞれ独立であり、互いに同一であっても異なっていても良く、前記Ｒ^１’基、前記Ｒ^２’基又は酸素原子である。Ｒ^４’が酸素原子である場合、Ｒ^４’基は結合して１つのエーテル基となって、ケイ素原子とともに環を形成しても良い。ａ’は同一であっても異なっていても良く０～１００であり、ｂ’は０～１００であり、ａ’＋ｂ’は０～２００である。但し、ｂ’が０の時はＲ^３’の少なくとも１つが前記Ｒ^２’基である。式（４）－１、（４）－２及び（５）中、Ｒ^５’は炭素数２～１０のアルキレン基又は炭素数７～１０のアラルキレン基、Ｒ^６’及びＲ^７’は炭素数２～６のアルキレン基であり、Ｒ^７’はエーテル結合であっても良く、ｃ’は０～２０、ｄ’は１～２０である。Ｒ^８’は、水素原子、エーテル基を含有していても良い炭素数１～５０の直鎖状若しくは分岐状のアルキル基、又はフェニル基である。） The silicone compound having a polyglycerin structure is preferably one represented by the following general formulas (4) and (5).

(In formulas (4) and (5), R ¹ ' are each independent and may be the same or different from each other, and are a hydrogen atom, a linear or branched alkyl group having 1 to 50 carbon atoms, or a phenyl group, and may contain an ether group or may be a silicone chain represented by general formula (6); R ² ' are a group having a polyglycerin group structure represented by formula (4)-1 or formula (4)-2; R ³ ' are each independent and may be the same or different from each other, and are the R ¹ ' group or the R ² 'group; R ⁴ ' are each independent and may be the same or different from each other, and are the R ¹ ' group, the R ² ' group, or an oxygen atom. When R ⁴ ' is an oxygen atom, R ⁴ The R 3 ' groups may be bonded to one ether group to form a ring together with the silicon atom. a' may be the same or different and is 0 to 100, b' is 0 to 100, and a'+b' is 0 to 200. However, when b' is 0, at least one of R ³ ' is the R ² ' group. In formulae (4)-1, (4)-2, and (5), R ⁵ ' is an alkylene group having 2 to 10 carbon atoms or an aralkylene group having 7 to 10 carbon atoms, R ⁶ ' and R ⁷ ' are alkylene groups having 2 to 6 carbon atoms, R ⁷ ' may be an ether bond, c' is 0 to 20, and d' is 1 to 20. R ^{8 '} is a hydrogen atom, a linear or branched alkyl group having 1 to 50 carbon atoms which may contain an ether group, or a phenyl group.)

Examples of silicone compounds having such a polyglycerin structure include the following:

（式中、ａ‘、ｂ’、ｃ’及びｄ’は上記のとおりである）

(wherein a', b', c' and d' are as defined above).

If the composition contains a silicone compound having such a polyglycerin structure, it will be able to exhibit better moisturizing properties, and as a result, it will be possible to obtain a bioelectrode composition that can form a biocontact layer that exhibits better sensitivity to ions released from the skin.

(Other additives)
The bioelectrode composition can also be mixed with inorganic particles such as silica particles, alumina particles, titania particles, and zirconia particles. The silica particles, alumina particles, titania particles, and zirconia particles have a hydrophilic surface, and are compatible with hydrophilic ionic polymers and polyglycerin silicones, and can improve the dispersibility of ionic polymers and polyglycerin silicones in hydrophobic silicone adhesives. The silica particles, alumina particles, titania particles, and zirconia particles can be preferably used in either dry or wet processes. The shape of the silica particles, alumina particles, titania particles, and zirconia particles can be any of spherical, elliptical, irregular, hollow, and porous. In addition, the surface of the particles such as silica can be surface-modified with a silane coupling agent or silicone.

<Method of manufacturing the bioelectrode composition>
The method for producing the bioelectrode composition of the present invention is not particularly limited. For example, (A) an ionic polymer material, (B) an addition reaction curing type silicone having at least a hydrosilyl group, and (C) a platinum group catalyst can be stored in separate containers, and when producing a bioelectrode, they can be mixed to form the bioelectrode composition.

In this way, it is preferable to store the ionic polymer material and the organohydrogensiloxane having hydrosilyl groups in separate containers, mix them with the platinum group catalyst just before curing by the hydrosilylation reaction, form a film by coating, and cure by the hydrosilylation reaction by baking. This is because solvents containing ionic polymer compounds contain trace amounts of moisture even after dehydration to remove moisture, and silanols are gradually generated during long-term storage.

In addition, when the above-mentioned component (D) is contained, the component (D) may be mixed into the component (A) or the component (B) before or simultaneously with mixing of the component (C).
This can reduce the effect of moisture from component (D).

(Dehydration treatment)
As mentioned above, it is not the silicone having hydrosilyl groups of the component (B) that is likely to contain water, but the solution containing the ionic polymer material of the component (A) containing a polar solvent. When mixed with the solution (B), the water contained in the solution (A) causes a deactivation reaction of the hydrosilyl groups. Therefore, the solution containing the ionic polymer compound of the component (A) is dehydrated as necessary. The dehydration treatment may be performed by a conventional method, for example, by azeotropic dehydration to increase the concentration of the solution containing the ionic polymer compound, or by using a dehydrating agent such as molecular sieves.

As described above, the bioelectrode composition of the present invention can efficiently transmit electrical signals from the skin to the device (i.e., has excellent electrical conductivity), is not likely to cause allergies even when worn on the skin for a long period of time (i.e., has excellent biocompatibility), is lightweight, can be manufactured at low cost, and can form a biocontact layer for a bioelectrode whose electrical conductivity does not decrease significantly even when wet or dried. In addition, the electrical conductivity can be further improved by adding a conductive powder (carbon powder, metal powder, etc.), and a bioelectrode with particularly high adhesive strength and high elasticity can be manufactured by combining it with a resin having adhesiveness and elasticity. Furthermore, the elasticity and adhesiveness to the skin can be improved by using additives, and the elasticity and adhesiveness can be adjusted by appropriately adjusting the composition of the resin and the thickness of the biocontact layer.

<Bioelectrode>
The present invention also provides a bioelectrode having a conductive substrate and a biocontact layer formed on the conductive substrate, the bioelectrode being a cured product of the bioelectrode composition of the present invention described above.

The bioelectrode of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited thereto.

Figure 1 is a schematic cross-sectional view showing an example of the bioelectrode of the present invention. The bioelectrode 1 in Figure 1 has a conductive substrate 2 and a biocontact layer 3 formed on the conductive substrate 2. The biocontact layer 3 is made of a cured product of the bioelectrode composition of the present invention. The biocontact layer 3 can contain a resin 6, an ionic polymer 5, and a conductivity enhancer 4. Below, with reference to Figures 1 and 2, a case where the biocontact layer 3 is a layer in which the conductivity enhancer 4 and the ionic polymer 5 are dispersed in the resin 6 will be described, but the bioelectrode of the present invention is not limited to this form.

When using such a bioelectrode 1 of FIG. 1, as shown in FIG. 2, the biocontact layer 3 (i.e., a layer in which the conductivity enhancer 4 and ionic polymer 5 are dispersed in the resin 6) is brought into contact with the living body 7, and an electrical signal is extracted from the living body 7 by the conductivity enhancer 4 and the ionic polymer 5, and this is conducted to a sensor device or the like (not shown) via the conductive substrate 2. In this way, with the bioelectrode of the present invention, the above-mentioned ionic polymer and conductivity enhancer can achieve both electrical conductivity and biocompatibility, and since it also has adhesiveness, the contact area with the skin is constant, and electrical signals from the skin can be obtained stably and with high sensitivity.

The constituent materials of the bioelectrode of the present invention are described in more detail below.

[Conductive substrate]
The bioelectrode of the present invention has a conductive substrate. This conductive substrate is usually electrically connected to a sensor device or the like, and conducts an electrical signal extracted from a living body via a living body contact layer to the sensor device or the like.

The conductive substrate is not particularly limited as long as it is conductive, but it is preferable that the conductive substrate contains at least one selected from the group consisting of gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, carbon, and conductive polymers.

The conductive substrate is not particularly limited and may be a hard conductive substrate, a flexible conductive film, a fabric coated with a conductive paste, or a fabric with a conductive polymer kneaded into it. The conductive substrate may be flat or uneven, or may be a mesh of woven metal wires, and may be selected appropriately depending on the application of the bioelectrode.

[Bio-contact layer]
The bioelectrode of the present invention has a biocontact layer formed on a conductive substrate. This biocontact layer is the part that actually comes into contact with the living body when the bioelectrode is used, and has electrical conductivity and adhesiveness. The biocontact layer is a cured product of the bioelectrode composition of the present invention, that is, an adhesive resin layer obtained by mixing the above-mentioned components (A), (B), and (C), applying the mixture, and then curing the mixture. The components (A) and (B) may contain polysiloxane having an alkenyl group and MQ resin, and may also contain components (D) and (E) as necessary.

The adhesive strength of the biological contact layer is preferably in the range of 0.5 N/25 mm to 20 N/25 mm. The adhesive strength is generally measured by the method shown in JIS Z 0237. A metal substrate such as SUS (stainless steel) or a PET (polyethylene terephthalate) substrate can be used as the substrate, but it can also be measured using human skin. The surface energy of human skin is lower than that of metals and various plastics, and is close to that of Teflon (registered trademark), making it less adhesive.

The thickness of the biocontact layer of the bioelectrode is preferably 1 μm to 5 mm, more preferably 2 μm to 3 mm. The thinner the biocontact layer, the weaker the adhesive strength, but the more flexible it is, the lighter it is, and the better it fits to the skin. The thickness of the biocontact layer can be selected taking into account the balance between adhesiveness and feel on the skin.

In addition, in the bioelectrode of the present invention, as in the case of conventional bioelectrodes (for example, the bioelectrode described in JP 2004-033468 A), a separate adhesive film may be provided on the biocontact layer to prevent the bioelectrode from peeling off from the living body during use. When providing a separate adhesive film, it is sufficient to form the adhesive film using an adhesive film material such as an acrylic type, a urethane type, or a silicone type. In particular, the silicone type has high oxygen permeability, so that the skin can breathe while it is attached, and has high water repellency, so that the adhesiveness is less likely to decrease due to sweat, and further, it is suitable because it is less irritating to the skin. In addition, in the bioelectrode of the present invention, as described above, peeling off from the living body can be prevented by adding an adhesive imparting agent to the bioelectrode composition or using a resin that has good adhesiveness to the living body, so the above-mentioned separate adhesive film is not necessarily required.

When using the bioelectrode of the present invention as a wearable device, there are no particular limitations on the wiring between the bioelectrode and the sensor device, and other components, and for example, those described in JP 2004-033468 A can be used.

As described above, the bioelectrode of the present invention has a biocontact layer formed of the cured product of the bioelectrode composition of the present invention, so that it can efficiently transmit electrical signals from the skin to the device (i.e., has excellent electrical conductivity), is not likely to cause allergies even when worn on the skin for a long period of time (i.e., has excellent biocompatibility), is lightweight, can be manufactured at low cost, and is a bioelectrode that does not significantly decrease in electrical conductivity even when wet or dried. In addition, the electrical conductivity can be further improved by adding conductive powder, and a bioelectrode with particularly high adhesive strength and high elasticity can be manufactured by combining it with a resin having adhesiveness and elasticity. Furthermore, the elasticity and adhesiveness to the skin can be improved by additives, and the elasticity and adhesiveness can be adjusted by appropriately adjusting the composition of the resin and the thickness of the biocontact layer. Therefore, such a bioelectrode of the present invention is particularly suitable as a bioelectrode to be used in a medical wearable device.

<Method of Manufacturing Bioelectrode>
The present invention also provides a method for manufacturing a bioelectrode having a conductive substrate and a biocontact layer formed on the conductive substrate, in which the bioelectrode composition of the present invention described above is applied to the conductive substrate and cured to form the biocontact layer.

The conductive substrate and other materials used in the method for manufacturing the bioelectrode of the present invention may be the same as those described above.

The method for applying the bioelectrode composition onto the conductive substrate is not particularly limited, but suitable methods include, for example, dip coating, spray coating, spin coating, roll coating, flow coating, doctor coating, screen printing, flexographic printing, gravure printing, and inkjet printing.

There are no particular limitations on the method for curing the resin, and it may be selected appropriately depending on the components (A) and (B) used in the bioelectrode composition. For example, it is preferable to activate a platinum group catalyst with either heat or light, or both, and cure the resin by an addition reaction with silicone that bonds to hydrosilyl groups and alkenyl groups.

The heating temperature is not particularly limited and may be selected appropriately depending on the components (A) and (B) used in the bioelectrode composition, but is preferably about 50 to 250°C.

When heating and light irradiation are combined, heating and light irradiation may be performed simultaneously, or heating may be performed after light irradiation, or light irradiation may be performed after heating. In addition, air drying may be performed after the coating film is heated in order to evaporate the solvent.

When the moisture content of components (A) and (B) is high or when component (A) is mixed with a solvent containing a hydroxyl group, carboxyl group, nitrogen atom, or thiol group, the deactivation reaction of the hydrosilyl group proceeds immediately after mixing components (A) and (B). In this case, components (A), (B), and (C) are mixed and left to stand, and then a bioelectrode is printed, cured, and attached to the skin to acquire a biosignal. After peeling it off, residue remains on the skin. This is because the deactivation of the hydrosilyl group causes a decrease in the crosslink density in the bioelectrode film, resulting in cohesive failure. The same phenomenon occurs even if the components are printed quickly after mixing, but if the time until curing, such as baking, is long.

By applying water droplets or spraying water vapor or mist onto the hardened film surface, it becomes more compatible with the skin, allowing biosignals to be obtained more quickly. Water mixed with alcohol can also be used to reduce the size of the vapor or mist droplets. The film surface can also be wetted by contacting it with absorbent cotton or cloth soaked in water.

The water that wets the surface of the cured film may contain salt. The water-soluble salt to be mixed with the water is selected from sodium salts, potassium salts, calcium salts, magnesium salts, and betaine.

Specific examples of the water-soluble salt include salts selected from sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium saccharin, acesulfame potassium, sodium carboxylate, potassium carboxylate, calcium carboxylate, sodium sulfonate, potassium sulfonate, calcium sulfonate, sodium phosphate, potassium phosphate, calcium phosphate, magnesium phosphate, and betaine. The above-mentioned polymer compound (A) is not included in the water-soluble salts.

More specifically, in addition to the above, sodium acetate, sodium propionate, sodium pivalate, sodium glycolate, sodium butyrate, sodium valerate, sodium caproate, sodium enanthate, sodium caprylate, sodium pelargonate, sodium caprate, sodium undecylate, sodium laurate, sodium tridecylate, sodium myristate, sodium pentadecylate, sodium palmitate, sodium margarate, sodium stearate, sodium benzoate, disodium adipate, disodium maleate, disodium phthalate, sodium 2-hydroxybutyrate, sodium 3-hydroxybutyrate, sodium 2-oxobutyrate, sodium gluconate, Examples of betaines include sodium tansulfonate, sodium 1-nonanesulfonate, sodium 1-decanesulfonate, sodium 1-dodecanesulfonate, sodium 1-undecanesulfonate, sodium cocoyl ethionate, sodium lauroyl methyl alanine, sodium cocoyl methyl taurate, sodium cocoyl glutamate, sodium cocoyl sarcosine, sodium lauroyl methyl taurate, laumidopropyl, potassium isobutyrate, potassium propionate, potassium pivalate, potassium glycolate, potassium gluconate, potassium methanesulfonate, calcium stearate, calcium glycolate, calcium gluconate, calcium 3-methyl-2-oxobutyrate, and calcium methanesulfonate. Betaine is a general term for intramolecular salts, specifically a compound in which three methyl groups are added to the amino group of an amino acid, and more specifically, trimethylglycine, carnitine, and proline betaine can be mentioned.

The water-soluble salt may further contain a monohydric alcohol or polyhydric alcohol having 1 to 4 carbon atoms, and the alcohol is preferably selected from ethanol, isopropyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, polyethylene glycol, polypropylene glycol, polyglycerin, diglycerin, or a silicone compound having a polyglycerin structure, and more preferably the silicone compound having a polyglycerin structure is one represented by the above general formulas (4) and (5).

In the pretreatment method using a water-soluble salt-containing aqueous solution, the bioelectrode membrane can be applied to the hardened bioelectrode membrane by spraying, dispensing water droplets, etc. It can also be applied in a high temperature and high humidity state such as a sauna. After application, in order to prevent drying, a protective film can be further laminated on the permeation layer to cover it. Since the protective film needs to be peeled off just before applying it to the skin, it can be coated with a release agent or a peelable Teflon (registered trademark) film can be used. For long-term storage, the dry electrode covered with the release film is preferably sealed in a bag covered with aluminum or the like. To prevent drying in the aluminum-covered bag, it is preferable to seal moisture in the bag.

Before attaching the bioelectrode of the present invention to the skin, the skin side can be moistened with water, alcohol, etc., or the skin can be wiped with a cloth or absorbent cotton containing water, alcohol, etc. The above-mentioned salt can also be contained in the water or alcohol.

As described above, the manufacturing method of the bioelectrode of the present invention makes it possible to easily manufacture, at low cost, the bioelectrode of the present invention, which has excellent electrical conductivity and biocompatibility, is lightweight, and whose electrical conductivity does not decrease significantly whether it is wet or dried.

The present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited to these. Note that "Me" represents a methyl group and "Vi" represents a vinyl group.

Synthesis Example 1
The ionic polymer 1 solution, which was mixed as an ionic material (conductive material) in the bioelectrode composition, was synthesized as follows. A 20% by mass PGMEA solution of each monomer was put into a reaction vessel and mixed, and the reaction vessel was cooled to -70°C under a nitrogen atmosphere, and degassed under reduced pressure and nitrogen blowing were repeated three times. After heating to room temperature, 0.01 mole of azobisisobutyronitrile (AIBN) was added as a polymerization initiator per mole of the total monomers, and the mixture was heated to 60°C and reacted for 15 hours. PGMEA was evaporated using an evaporator to concentrate the polymer to 30% by mass, and water was evaporated at the same time. The composition of the obtained polymer was confirmed by ¹ H-NMR after drying a part of the polymer solution. The molecular weight (Mw) and dispersity (Mw/Mn) of the obtained polymer were confirmed by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 1 in PGMEA Mw=38,100
Mw/Mn=1.91

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 2
In the same manner as in Synthesis Example 1, a solution of ionic polymer 2 was prepared using 2-heptanone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 2 in 2-heptanone Mw=32,100
Mw/Mn=1.99

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 3
In the same manner as in Synthesis Example 1, a solution of ionic polymer 3 was prepared using 2-ethoxycarbonylcyclopentanone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 3 in 2-ethoxycarbonylcyclopentanone Mw=33,300
Mw/Mn=1.83

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 4
In the same manner as in Synthesis Example 1, a solution of ionic polymer 4 was prepared using cyclohexanone as the polymerization solvent.

30% by weight solution of ionic polymer 4 in cyclohexanone Mw=80,100
Mw/Mn=2.15

Synthesis Example 5
In the same manner as in Synthesis Example 1, a solution of ionic polymer 5 was prepared using cyclopentanone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 5 in cyclopentanone Mw=44,400
Mw/Mn=1.94

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 6
In the same manner as in Synthesis Example 1, a solution of ionic polymer 6 was prepared using 2-propylcyclohexanone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 6 in 2-propylcyclohexanone Mw=41,100
Mw/Mn=1.86

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 7
In the same manner as in Synthesis Example 1, a solution of ionic polymer 7 was prepared using 2-acetylcyclohexanone as the polymerization solvent.

30% by weight solution of ionic polymer 7 in 2-acetylcyclohexanone Mw=43,600
Mw/Mn=1.93

Synthesis Example 8
In the same manner as in Synthesis Example 1, a solution of ionic polymer 8 was prepared using 2-pentyl-2-cyclopenten-1-one as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 8 in 2-pentyl-2-cyclopenten-1-one Mw=35,700
Mw/Mn=2.06

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 9
In the same manner as in Synthesis Example 1, a solution of ionic polymer 9 was prepared using 2-heptylcyclopentanone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 9 in 2-heptylcyclopentanone Mw=55,100
Mw/Mn=2.02

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 10
In the same manner as in Synthesis Example 1, a solution of ionic polymer 10 was prepared using 3,3,5-trimethylcyclohexanone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 10 in 3,3,5-trimethylcyclohexanone Mw=87,500
Mw/Mn=2.01

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 11
In the same manner as in Synthesis Example 1, a solution of ionic polymer 11 was prepared using 2-methoxycarbonylcyclopentanone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 11 in 2-methoxycarbonylcyclopentanone Mw=41,600
Mw/Mn=1.91

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 12
In the same manner as in Synthesis Example 1, a solution of ionic polymer 12 was prepared using γ-valerolactone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by mass solution of ionic polymer 12 in γ-valerolactone Mw 36,100
Mw/Mn=1.55

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 13
In the same manner as in Synthesis Example 1, a solution of ionic polymer 13 was prepared using ε-caprolactone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 13 in ε-caprolactone Mw=38,300
Mw/Mn=2.01

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 14
In the same manner as in Synthesis Example 1, a solution of ionic polymer 14 was prepared using cycloheptanone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 14 in cycloheptanone Mw=33,500
Mw/Mn=1.97

(The number of repetitions in the formula indicates the average value.)

Synthesis Example 15
In the same manner as in Synthesis Example 1, a solution of ionic polymer 15 was prepared using 3-methylcyclohexanone as the polymerization solvent.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of ionic polymer 15 in 3-methylcyclohexanone Mw=34,900
Mw/Mn=1.91

(The number of repetitions in the formula indicates the average value.)

（式中の繰り返し数は平均値を示す。） Synthesis Example 16
In the same manner as in Synthesis Example 1, a solution of ionic polymer 16 was prepared using diethylene glycol diethyl ether as a polymerization solvent.
30% by weight solution of ionic polymer 16 in diethylene glycol diethyl ether Mw=43,100
Mw/Mn=1.74

(The number of repetitions in the formula indicates the average value.)

（式中の繰り返し数は平均値を示す。） Synthesis Example 17
In the same manner as in Synthesis Example 1, a solution of ionic polymer 17 was prepared using diethylene glycol methyl butyl ether as a polymerization solvent.
30% by weight solution of ionic polymer 17 in diethylene glycol methyl butyl ether Mw=42,000
Mw/Mn=1.77

(The number of repetitions in the formula indicates the average value.)

（式中の繰り返し数は平均値を示す。） Synthesis Example 18
In the same manner as in Synthesis Example 1, a solution of ionic polymer 18 was prepared using diethylene glycol dibutyl ether as a polymerization solvent.
30% by weight solution of ionic polymer 18 in diethylene glycol dibutyl ether Mw=41,000
Mw/Mn=1.69

(The number of repetitions in the formula indicates the average value.)

（式中の繰り返し数は平均値を示す。） Synthesis Example 19
In the same manner as in Synthesis Example 1, a solution of ionic polymer 19 was prepared using diethylene glycol butyl ether acetate as a polymerization solvent.
30% by weight solution of ionic polymer 19 in diethylene glycol butyl ether acetate Mw=37,000
Mw/Mn=1.61

(The number of repetitions in the formula indicates the average value.)

（式中の繰り返し数は平均値を示す。） Synthesis Example 20
An ionic polymer 20 solution was prepared in the same manner as in Synthesis Example 19, except that the ionic monomer was changed and diethylene glycol butyl ether acetate was used as the polymerization solvent.
30% by weight solution of ionic polymer 20 in diethylene glycol butyl ether acetate Mw=39,000
Mw/Mn=1.64

(The number of repetitions in the formula indicates the average value.)

（式中の繰り返し数は平均値を示す。） Synthesis Example 21
An ionic polymer 21 solution was prepared in the same manner as in Synthesis Example 19, except that the ionic monomer was changed and diethylene glycol butyl ether acetate was used as the polymerization solvent.
30% by weight solution of ionic polymer 21 in diethylene glycol butyl ether acetate Mw=44,000
Mw/Mn=1.68

(The number of repetitions in the formula indicates the average value.)

（式中の繰り返し数は平均値を示す。） Synthesis Example 22
An ionic polymer 22 solution was prepared in the same manner as in Synthesis Example 19, except that the ionic monomer was changed and diethylene glycol butyl ether acetate was used as the polymerization solvent.
30% by weight solution of ionic polymer 22 in diethylene glycol butyl ether acetate Mw=48,000
Mw/Mn=1.81

(The number of repetitions in the formula indicates the average value.)

Comparative Synthesis Example 1
A comparative ionic polymer 1 solution was prepared by polymerization in the same manner as in Synthesis Example 1, using cyclopentanone as a polymerization solvent at a concentration of 30% by mass, without carrying out a dehydration treatment.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of comparative ionic polymer 1 in cyclopentanone Mw=44,400
Mw/Mn=1.98

(The number of repetitions in the formula indicates the average value.)

Comparative Synthesis Example 2
A comparative ionic polymer 2 solution was prepared in the same manner as in Synthesis Example 1, except that polymerization was carried out using PGEE in a polymerization solvent at a concentration of 30% by mass, without carrying out a dehydration treatment.

（式中の繰り返し数は平均値を示す。） 30% by weight PGEE solution of comparative ionic polymer 2 Mw=46,600
Mw/Mn=1.95

(The number of repetitions in the formula indicates the average value.)

Comparative Synthesis Example 3
Polymerization was carried out in the same manner as in Synthesis Example 1, using diacetone alcohol as the polymerization solvent, to prepare a comparative ionic polymer 3 solution.

（式中の繰り返し数は平均値を示す。） 30% by weight solution of comparative ionic polymer 3 in diacetone alcohol Mw=36,600
Mw/Mn=1.92

(The number of repetitions in the formula indicates the average value.)

Polyglycerin silicone compounds 1 to 5 (additives) are shown below. The synthesis method for these compounds is as described in JP 2019-99469 A, and they were synthesized by hydrosilylation reaction of a silicone compound having a SiH group and a polyglycerin compound having a double bond in the presence of a platinum catalyst.

Siloxane compounds 1 to 4 that were blended into the bioelectrode composition as silicone-based resins are shown below.

(Siloxane Compound 1)
Siloxane compound 1 was a vinyl-containing polydimethylsiloxane having a viscosity of 27,000 mPa·s in a 30% toluene solution, an alkenyl group content of 0.007 mol/100 g, and molecular chain terminals blocked with SiMe ₂ Vi groups.

(Siloxane Compound 2)
A 60% Isopar G solution of MQ resin polysiloxane consisting of Me ₃ SiO _0.5 units and SiO ₂ units (Me ₃ SiO _0.5 units/SiO ₂ units=0.8) was used as siloxane compound 2.

(Siloxane Compound 3)
A solution consisting of 40 parts by mass of vinyl-containing polydimethylsiloxane having a viscosity of 42,000 mPa·s in a 30% toluene solution, an alkenyl group content of 0.007 mol/100 g, and whose molecular chain ends are blocked with OH, 100 parts by mass of a ₆₀ % Isopar G solution of MQ resin polysiloxane consisting of _Me3SiO0.5 units and _SiO2 units ( _{Me3SiO0.5 units} / _SiO2 units=0.8), and 26.7 parts by mass of Isopar G was heated under reflux for 4 hours and then cooled to obtain siloxane compound 3 in which the polydimethylsiloxane was bonded to the MQ resin.

(Siloxane Compound 4)
As the silicone having a hydrosilyl group, KF-99 manufactured by Shin-Etsu Chemical Co., Ltd. was used.

The silicone resin used was KF-353, a polyether-type silicone oil with side chain polyether modification manufactured by Shin-Etsu Chemical Co., Ltd.

The organic solvents contained in the bioelectrode composition are shown below.
PGMEA: Propylene glycol-1-monomethyl ether-2-acetate PGEE: 1-ethoxy-2-propanol DAA: Diacetone alcohol Isopar G: Isoparaffin-based solvent manufactured by Standard Oil Isopar M: Isoparaffin-based solvent manufactured by Standard Oil

The platinum catalyst, conductivity enhancer (metal powder, carbon black, carbon nanotube, lithium titanate, graphite, ion-treated graphite, ion-treated carbon black, metal chloride), and additive (addition reaction control agent) blended as additives in the bioelectrode composition are shown below.
Platinum catalyst: CAT-PL-56 (platinum content 2% by mass) manufactured by Shin-Etsu Chemical Co., Ltd.
Metal powder Silver powder: Sigma-Aldrich silver flakes, diameter 10 μm
Gold powder: Sigma-Aldrich gold powder, diameter 10 μm or less Carbon black: Denka Black Li-400, Denka
Multi-walled carbon nanotubes: Sigma-Aldrich, diameter 110-170 nm, length 5-9 μm
Lithium titanate powder, spinel: manufactured by Sigma-Aldrich, size 200 nm or less Graphite: manufactured by Sigma-Aldrich, diameter 20 μm or less Ion-treated graphite 1: prepared according to Preparation Example 1 below.
Ion-treated carbon black 1, 2: Prepared according to Preparation Examples 2 and 3 below.
Metal chloride powder Sodium chloride powder: Powder form
Potassium chloride powder: Powder type Addition reaction inhibitor: 1-ethynylcyclohexanol

(Preparation Example 1)
10% by mass of the graphite dispersed in methanol containing 1% by mass of sodium chloride was stirred at 60° C. for 10 hours, and the methanol was evaporated to prepare ion-treated graphite 1.

(Preparation Example 2)
10% by mass of the Denka Black Li-400 dispersed in methanol containing 1% by mass of sodium chloride was stirred at 60° C. for 10 hours, and the methanol was evaporated to prepare ion-treated carbon black 1.

(Preparation Example 3)
Ion-treated carbon black 2 was prepared in the same manner as in Preparation Example 2, except that sodium chloride was replaced with the above potassium chloride.

[Examples 1 to 27, Comparative Examples 1 to 3]
In the compositions shown in Tables 1 to 3, ionic polymers (ionic polymers), hydrosilyl group-containing silicones, silicone resins, organic solvents, conductivity enhancers, and additives (polyglycerin, addition reaction control agents) were blended to prepare components (A) and (B), which were then mixed with component (C) in the ratios shown in Tables 4 and 5. The moisture content (mass%) of component (A) (solutions A 1 to 26, comparative solutions A 1 to 3) and component (B) (solutions B 1 to 3) was measured by the Karl Fischer method. The moisture content in the bioelectrode composition obtained by mixing components (A), (B), and (C) can be calculated from the amounts (parts by mass) and moisture content of components (A) and (B), since the blending ratio of component (C) is small and the moisture derived from it can be ignored. In Examples 1 to 27, the moisture content in each bioelectrode composition was 0.2 mass% or less.

(Biological signal evaluation)
A conductive paste made by Fujikura Kasei, Dotite FA-333, was coated on a thermoplastic urethane (TPU) film ST-604 made by Bemis by screen printing, and baked in an oven at 120°C for 10 minutes to print a keyhole-shaped conductive pattern with a circle diameter of 2 cm. A mixture of components A to C (bioelectrode composition) described in Tables 1 to 3 was applied by screen printing on the circular part on top of the film after 1 hour from mixing, and then air-dried at room temperature for 10 minutes, and baked in an oven at 125°C for 10 minutes to evaporate the solvent and harden the film to produce a bioelectrode (Figure 3). The urethane film on which the bioelectrode was printed was cut out, and double-sided tape was attached to it to produce three bioelectrodes (bioelectrode samples) for each composition solution (Figure 4). Here, Figure 3 is a diagram showing a bioelectrode 1 in which a conductive pattern 2 is printed on a thermoplastic urethane film 20 and a biocontact layer 3 is produced by hardening the conductive pattern 2. FIG. 4 shows a bioelectrode sample 10 obtained by cutting out a thermoplastic urethane film 20 on which a conductive pattern 2 has been printed and cured, and attaching a double-sided tape 21 to the cut piece.

(Measurement of the thickness of the biological contact layer)
The thickness of the biocontact layer of the bioelectrode prepared above was measured using a micrometer. The results are shown in Tables 4 and 5.

(Measurement of biological signals)
The conductive wiring pattern of the conductive paste of the bioelectrode was connected to a portable electrocardiograph HCG-901 manufactured by Omron Healthcare Co., Ltd. with a conductive wire, and the positive electrode of the electrocardiograph was attached to the LA position of the human body in Fig. 5, the negative electrode to the LL position, and the earth to the RA position. 20 minutes after attachment, the measurement of the electrocardiogram was started, and it was confirmed whether an electrocardiogram waveform (ECG signal) consisting of P, Q, R, S, and T waves shown in Fig. 6 appeared, and it was observed whether residue of the bioelectrode film was generated on the skin after the bioelectrode was peeled off. The results are shown in Tables 4 and 5.

As shown in Tables 4 and 5, in Examples 1 to 27 in which the biocontact layer was formed using a bioelectrode composition of the present invention prepared using a solution with a water content reduced to 0.2% or less, or a solvent containing an ether, ester, or ketone that does not contain a hydroxyl group, carboxyl group, nitrogen atom, or thiol group as component (A), good biosignals were obtained and no residue was left on the skin after peeling.

On the other hand, when a bioelectrode composition with a moisture content exceeding 0.2% was used, or when a solvent containing a hydroxyl group (DAA) was used, biosignals could be obtained, but residue was left on the skin after removal (Comparative Examples 1 to 3).

From the above, a bioelectrode in which a biocontact layer is formed using the bioelectrode composition of the present invention has excellent electrical conductivity, biocompatibility, and adhesion to conductive substrates, and because of its high ionic conductivity, it can obtain good biosignals, and because the crosslinking reaction within the membrane proceeds sufficiently without inhibiting the addition reaction, no residue is left on the skin even after peeling off.

The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included within the technical scope of the present invention.

1...bioelectrode, 2...conductive substrate (conductive pattern), 3...biocontact layer, 4...conductivity enhancer, 5...ionic polymer, 6...resin, 7...bioorganism, 10...bioelectrode sample, 20...thermoplastic urethane film, 21...double-sided tape.

Claims (22)

A bioelectrode composition containing (A) an ionic polymer material, (B) an addition reaction curing type silicone having at least a hydrosilyl group, (C) a platinum group catalyst, and a solvent, the bioelectrode composition having a moisture content of 0.2 mass% or less, and the solvent containing one or more of ether-based, ester-based, and ketone-based solvents that do not contain a hydroxyl group, a carboxyl group, a nitrogen atom, or a thiol group. The bioelectrode composition is a mixture of a solution containing the ionic polymer material as component (A), the addition reaction curing type silicone having at least a hydrosilyl group as component (B), and the platinum group catalyst as component (C),
2. The bioelectrode composition according to claim 1, wherein the moisture content in each of the components (A) and (B) is 0.2 mass % or less. The bioelectrode composition according to claim 2, characterized in that the solvent of the solution of the component (A) is one or more of ether-based, ester-based, and ketone-based solvents that do not contain a hydroxyl group, a carboxyl group, a nitrogen atom, or a thiol group, and the component (B) is solvent-free or a solution of a hydrocarbon-based or ether-based solvent. The bioelectrode composition according to any one of claims 1 to 3, characterized in that the ionic polymer material in component (A) is a polymer compound containing a repeating unit having a structure selected from the sodium salt, potassium salt, and silver salt of any of fluorosulfonic acid, fluorosulfonimide, and N-carbonylfluorosulfonamide. The bioelectrode composition according to claim 4, characterized in that the structure is represented by the following general formulas (1)-1 to (1)-4.

(In the formula, Rf ₁ and Rf ₂ are a hydrogen atom, a fluorine atom, an oxygen atom, a methyl group, or a trifluoromethyl group. When Rf ₁ is an oxygen atom, Rf ₂ is also an oxygen atom and forms a carbonyl group together with the carbon atom to which it is bonded. Rf ₃ and Rf ₄ are a hydrogen atom, a fluorine atom, or a trifluoromethyl group, and at least one of Rf ₁ to Rf ₄ is a fluorine atom or a trifluoromethyl group. Rf ₅ , Rf ₆ , and Rf ₇ are a fluorine atom, a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 3 or 4 carbon atoms, and have at least one fluorine atom. m is an integer of 1 to 4. M is sodium, potassium, or silver.) The bioelectrode composition according to claim 5, characterized in that the one or more repeating units selected from the sodium salt, potassium salt, and silver salt of fluorosulfonic acid represented by the general formula (1)-1 or (1)-2, sulfonimide represented by the general formula (1)-3, or sulfonamide represented by the general formula (1)-4 are repeating units having one or more repeating units selected from the repeating units a1 to a7 represented by the following general formula (2).

(In the formula, R ¹ , R ³ , R ⁵ , R ⁸ , R ¹⁰ , R ¹¹ and R ¹³ are each independently a hydrogen atom or a methyl group; R ² , R ⁴ , R ⁶ , R ⁹ and R ¹² are each independently a single bond, an ester group, or a linear, branched or cyclic divalent hydrocarbon group having 1 to 13 carbon atoms which may have an ether group, an ester group or both; R ⁷ is a linear, branched or cyclic alkylene group having 1 to 4 carbon atoms or a branched alkylene group having 3 to 12 carbon atoms, and one or two of the hydrogen atoms in R ⁷ may be substituted with a fluorine atom; X ₁ , X ₂ , X ₃ , X ₄ and X ₆ are each independently a single bond, a phenylene group, a naphthylene group, an ether group, an ester group or an amide group; X _{X 5} is a single bond, an ether group, or an ester group, X ₇ is a single bond, an arylene group having 6 to 12 carbon atoms, or -C(=O)-O-X ₁₀ -, X ₁₀ is a linear, branched, or cyclic alkylene group having 1 to 12 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 10 carbon atoms, and X ₁₀ may have an ether group, a carbonyl group, or an ester group. Y is an oxygen atom or a -NR ¹⁹ - group, R ¹⁹ is a hydrogen atom, or a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 3 or 4 carbon atoms, and Y and R ⁴ may be bonded to form a ring. m is an integer of 1 to 4. a1, a2, a3, a4, a5, a6, and a7 are numbers satisfying 0≦a1≦1.0, 0≦a2≦1.0, 0≦a3≦1.0, 0≦a4≦1.0, 0≦a5≦1.0, 0≦a6≦1.0, and 0≦a7≦1.0, and 0<a1+a2+a3+a4+a5+a6+a7≦1.0. M, Rf ₅ , Rf ₆ , and Rf ₇ are the same as those described above. The bioelectrode composition according to any one of claims 1 to 6, characterized in that the component (B) contains an organopolysiloxane having a hydrosilyl group. The bioelectrode composition according to any one of claims 1 to 7, characterized in that the (B) component contains a diorganopolysiloxane having an alkenyl group in addition to an organopolysiloxane having a hydrosilyl group. The bioelectrode composition according to any one of claims 1 to 8, characterized in that the component (B) further contains a silicone resin having R _x SiO _(4-x)/2 units (R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and x is in the range of 2.5 to 3.5) and SiO ₂ units. The bioelectrode composition according to any one of claims 1 to 9, characterized in that the component (A) contains a diorganosiloxane having an alkenyl group in addition to an ionic polymer material. The bioelectrode composition according to claim 10, characterized in that the component (A) further contains a silicone resin having R _x SiO _(4-x)/2 units (R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and x is in the range of 2.5 to 3.5) and SiO ₂ units. The bioelectrode composition according to any one of claims 1 to 11, further comprising, as component (D), one or more selected from carbon powder, metal powder, silicon powder, lithium titanate powder, and metal chloride powder in the component (A) or the component (B). The bioelectrode composition according to claim 12, characterized in that the carbon powder is any one of carbon black, graphite, and carbon nanotubes, or a combination thereof. The bioelectrode composition according to claim 13, characterized in that the carbon powder further contains an ionic component. The bioelectrode composition according to claim 12, characterized in that the metal powder is a metal powder selected from gold, silver, platinum, copper, tin, titanium, nickel, aluminum, tungsten, molybdenum, ruthenium, chromium, and indium. The bioelectrode composition according to claim 15, characterized in that the metal powder is silver powder. The method for producing a bioelectrode composition according to any one of claims 1 to 16, characterized in that the (A) ionic polymer material, the (B) addition reaction curing type silicone having at least a hydrosilyl group, and the (C) platinum group catalyst are stored in separate containers, and when producing a bioelectrode, they are mixed to produce the bioelectrode composition. The method for producing a bioelectrode composition according to claim 12, characterized in that the (D) component is mixed into the (A) component or the (B) component before or simultaneously with mixing the (C) component. A bioelectrode having a conductive substrate and a biocontact layer formed on the conductive substrate, the bioelectrode being characterized in that the biocontact layer is a cured product of the bioelectrode composition according to any one of claims 1 to 16. The bioelectrode according to claim 19, characterized in that the conductive substrate contains one or more selected from gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, carbon, and conductive polymers. A method for manufacturing a bioelectrode having a conductive substrate and a biocontact layer formed on the conductive substrate, the method being characterized in that the bioelectrode composition according to any one of claims 1 to 16 is applied to the conductive substrate and cured to form the biocontact layer. The method for manufacturing a bioelectrode according to claim 21, characterized in that the conductive base material contains at least one selected from gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, carbon, and conductive polymers.

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